INDIANAPOLIS (AP) — About 727,000 Indiana residents will soon receive a second round of voter registration postcards as part of state officials’ ongoing push to remove potentially inaccurate voter registrations from the rolls.

The postcards are being sent only to voters whose first postcards were returned in late May because of undeliverable addresses. Of that initial wave of 4.4 million postcards, 16 percent were returned to the state.

The postcards being sent this week are forwardable and urge the voters to update their address and voter registration data. Secretary of State Connie Lawson said those who receive the postcards must confirm or update their voter information by July 24.

If they don’t act, they’ll be classified as inactive. However, those people can still vote, but they could be removed from the rolls if they don’t do so before 2017.

Nationwide, 1.8 million dead people remain on voter lists, Lawson said, citing Pew Research Center data, and 2.7 million people are registered in more than one state.

Lawson said the Legislature allocated $2.1 million to pay for the mailings, which are the key part of the voter registration file update. A similar update in 2006 removed 600,000 duplicate or inaccurate voter registration records.

She said that county offices receive information from the Bureau of Motor Vehicles, State Department of Health, Social Security Administration and Department of Correction to try to keep the lists fresh and accurate.

Lawson said it’s impossible to know how much Indiana’s inflated voter registration lists affect the turnout rate. She said that in some counties, there are more registered voters than adult residents.

In Indiana’s May primary, statewide turnout was 13 percent — the lowest number in more than two decades.